Solid-state imaging device, method of manufacturing a solid-state imaging device, and electronic apparatus

ABSTRACT

Provided is a solid-state imaging device including a lamination-type backside illumination CMOS (Complementary Metal Oxide Semiconductor) image sensor having a global shutter function. The solid-state imaging device includes a separation film including one of a light blocking film and a light absorbing film between a memory and a photo diode.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/531,547, filed Nov. 3, 2014, which claims priority to Japanese PatentApplication No. JP 2013-231975, filed Nov. 8, 2013, the entiredisclosures of which are hereby incorporated herein by reference.

BACKGROUND

The present disclosure relates to a solid-state imaging device, a methodof manufacturing a solid-state imaging device, and an electronicapparatus, and more particularly, to a solid-state imaging device, amethod of manufacturing a solid-state imaging device, and an electronicapparatus that are capable of suppressing the generation of aliasing andimproving the saturation signal amounts of a photo diode (PD) and amemory and sensitivity of the photo diode.

In a backside illumination CMOS (Complementary Metal OxideSemiconductor) image sensor having a global shutter function in relatedart, a photo diode (PD) and a memory that temporarily accumulates charge(signal) transferred from the photo diode are provided on the same planeof a substrate.

For that reason, an area where each of the photo diode and the memory isprovided is limited, and this prevents saturation signal amounts of thephoto diode and the memory from being increased or sensitivity of thephoto diode from being improved.

In this regard, these days, a lamination-type backside illumination CMOSimage sensor having a global shutter function is developed (JapanesePatent Application Laid-open Nos. 2012-084644, 2010-212668, and2011-166170).

In the lamination-type backside illumination CMOS image sensor having aglobal shutter function, a photo diode is disposed on a light incidentside and a memory is laminated on a wiring layer side, and thus areas ofthe photo diode and the memory can be enlarged at the same pixel pitchas well.

As a result, it is possible to increase the saturation signal amounts ofthe photo diode and the memory and improve the sensitivity of the photodiode.

SUMMARY

In the lamination-type backside illumination CMOS image sensor having aglobal shutter function, however, the photo diode and the memory areconfigured so as to be separated from each other by a dopant, and thusincident light from the backside surface passes through the photo diodeand an element separation film and enters the memory in some cases.

In this case, the incident light may be subjected to photoelectricconversion in the memory and detected as aliasing at an unintendedtiming.

Further, also in the lamination-type backside illumination CMOS imagesensor having a global shutter function, a space for providing each ofthe photo diode and the memory is limited, and this prevents thesaturation signal amounts of the photo diode and the memory from beingincreased and the sensitivity of the photo diode from being improved.

In view of the circumstances as described above, in particular, it isdesirable to provide a light blocking film or a light absorbing filmthat blocks or absorbs, respectively, light that passes through thephoto diode, as a separation film that separates the photo diode and thememory from each other, to thus suppress the entry of the light to thememory and suppress the generation of aliasing. Additionally, it is alsodesirable to increase spaces for the photo diode and the memory in size,to thus increase the saturation signal amounts of the photo diode andthe memory and improve the sensitivity of the photo diode.

According to an embodiment of the present disclosure, there is provideda solid-state imaging device including a lamination-type backsideillumination CMOS (Complementary Metal Oxide Semiconductor) image sensorhaving a global shutter function, the solid-state imaging deviceincluding a separation film including one of a light blocking film and alight absorbing film between a memory and a photo diode.

The solid-state imaging device may further include a vertical transistorconfigured to transfer charge from the photo diode to the memory.

The solid-state imaging device may further include a floating diffusion,in which the vertical transistor may be disposed at an end of the photodiode such that a pitch of the photo diode coincides with a pitch of thevertical transistor, the memory, and the floating diffusion.

The solid-state imaging device may further include a floating diffusion,in which the vertical transistor may be disposed at the center of thephoto diode such that a pitch of the photo diode coincides with a pitchof the vertical transistor, the memory, and the floating diffusion.

The solid-state imaging device may further include a floating diffusion,in which the photo diode, the memory, and the floating diffusion may beprovided on respective layers and laminated on one another, to form athree-layer structure.

The separation film including the light blocking film may be formed ofmetal.

A negative potential may be applied to the separation film including thelight blocking film and being formed of metal.

The separation film including the light blocking film and being formedof metal may be connected to an outside of a pixel array.

The separation film including the light absorbing film may include afilm formed of a compound semiconductor having a chalcopyrite structure.

According to another embodiment of the present disclosure, there isprovided an electronic apparatus including a solid-state imaging deviceincluding a lamination-type backside illumination CMOS (ComplementaryMetal Oxide Semiconductor) image sensor having a global shutterfunction, the electronic apparatus including a separation film includingone of a light blocking film and a light absorbing film between a memoryand a photo diode.

According to another embodiment of the present disclosure, there isprovided a method of manufacturing a solid-state imaging deviceincluding a lamination-type backside illumination CMOS (ComplementaryMetal Oxide Semiconductor) image sensor having a global shutterfunction, the solid-state imaging device including a separation filmincluding one of a light blocking film and a light absorbing filmbetween a memory and a photo diode, the method including: a first stepof forming an insulating film on one surface of a first substrate onwhich the memory is formed and an insulating film on one surface of asecond substrate on which the photo diode is formed, and forming theseparation film on the insulating film of the first substrate and theseparation film on the insulating film of the second substrate; a secondstep of bonding the first substrate and the second substrate to eachother, with the surface of the first substrate on which the separationfilm is formed and the surface of the second substrate on which theseparation film is formed facing each other, to form an integratedsubstrate; and a third step of thinning the integrated substrate.

The first step may include forming an SCF (Si cover film) on each of theone surface of the first substrate and the one surface of the secondsubstrate before the insulating films are formed.

The method of manufacturing a solid-state imaging device may furtherinclude a fourth step of forming the photo diode on a surface that isdifferent from the surface of the second substrate on which theinsulating film is formed, after the insulating films and the separationfilms are formed in the first step and before the second step isperformed.

The method of manufacturing a solid-state imaging device may furtherinclude a fourth step of forming the photo diode on a surface that isdifferent from the surface of the second substrate on which theinsulating film is formed, after the third step is performed.

According to another embodiment of the present disclosure, there isprovided a solid-state imaging device manufactured by a method ofmanufacturing a solid-state imaging device including a lamination-typebackside illumination CMOS (Complementary Metal Oxide Semiconductor)image sensor having a global shutter function, the solid-state imagingdevice including a separation film including one of a light blockingfilm and a light absorbing film between a memory and a photo diode, themethod including: a first step of forming an insulating film on onesurface of a first substrate on which the memory is formed and aninsulating film on one surface of a second substrate on which the photodiode is formed, and forming the separation film on the insulating filmof the first substrate and the separation film on the insulating film ofthe second substrate; a second step of bonding the first substrate andthe second substrate to each other, with the surface of the firstsubstrate on which the separation film is formed and the surface of thesecond substrate on which the separation film is formed facing eachother, to form an integrated substrate; and a third step of thinning theintegrated substrate.

In one embodiment of the present disclosure, the solid-state imagingdevice including a lamination-type backside illumination CMOS(Complementary Metal Oxide Semiconductor) image sensor having a globalshutter function includes a separation film including one of a lightblocking film and a light absorbing film between a memory and a photodiode.

According to one embodiment of the present disclosure, particularly, itis possible to suppress the generation of aliasing in the imaging of asolid-state imaging device, and to increase the saturation signalamounts and the sensitivity of a photo diode (PD) and a memory.

These and other objects, features and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional side view of a structure example of a solid-stateimaging device in related art;

FIG. 2 is a diagram showing a circuit configuration example of asolid-state imaging device to which an embodiment of the presentdisclosure is applied;

FIG. 3 is a first sectional side view of a structure example of asolid-state imaging device to which an embodiment of the presentdisclosure is applied;

FIG. 4 is a second sectional side view of a structure example of asolid-state imaging device to which an embodiment of the presentdisclosure is applied;

FIG. 5 is a third sectional side view of a structure example of asolid-state imaging device to which an embodiment of the presentdisclosure is applied;

FIG. 6 is a fourth sectional side view of a structure example of asolid-state imaging device to which an embodiment of the presentdisclosure is applied;

FIG. 7 is a flowchart for describing a first method of manufacturing asolid-state imaging device to which an embodiment of the presentdisclosure is applied;

FIG. 8 is a diagram for describing the first method of manufacturing asolid-state imaging device to which an embodiment of the presentdisclosure is applied;

FIG. 9 is a flowchart for describing a second method of manufacturing asolid-state imaging device to which an embodiment of the presentdisclosure is applied; and

FIG. 10 is a diagram for describing the second method of manufacturing asolid-state imaging device to which an embodiment of the presentdisclosure is applied.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, modes for carrying out the present disclosure (hereinafter,referred to as embodiments) will be described. It should be noted thatdescription will be given in the following order.

-   -   1. First Embodiment (example of connecting vertical transistor        to end of photo diode)    -   2. Second Embodiment (example of connecting vertical transistor        to center of photo diode)    -   3. Third Embodiment (example of connecting photo diode and        transistor by implant plug)    -   4. Fourth Embodiment (example of laminating photo diode, memory,        and floating diffusion in three layers)    -   5. Fifth Embodiment (example of manufacturing method when photo        diode is first provided on substrate)    -   6. Sixth Embodiment (example of manufacturing method when photo        diode is lastly provided on substrate)

1. First Embodiment Structure of General Solid-State Imaging Device

FIG. 1 is a sectional side view of a solid-state imaging device thatforms a backside illumination CMOS (Complementary Metal OxideSemiconductor) image sensor with a global shutter function, which hasbeen generally used in the past.

The backside illumination CMOS image sensor with a global shutterfunction includes a microlens ML, a color filter CF, a photo diode PD, amemory MEM, a floating diffusion FD, and transistors TrA and TrB, whichare disposed in the stated order from the bottom of FIG. 1 in a lightincident direction.

The microlens ML inputs the incident light into the color filter CF in asubsequent stage. The color filter CF causes the incident light with theaddition of a color of R, G, B, or the like to pass therethrough andinputs the light into the photo diode PD. The photo diode PD generatescharge by photoelectric conversion based on the incident light, thecharge corresponding to the amount of the incident light. The transistorTrB transfers the charge generated in the photo diode PD to the memoryMEM at a predetermined timing based on a control signal from acontroller (not shown). Further, the transistor TrA transfers the chargeaccumulated in the memory MEM to the floating diffusion FD at apredetermined timing based on a control signal from the controller (notshown). An amplification transistor (not shown) generates an amplifiedsignal corresponding to the charge supplied from the floating diffusionFD. The amplified signal is output as a light receiving signal at apredetermined timing via a selected transistor.

Incidentally, as shown in FIG. 1, the solid-state imaging device inrelated art blocks or absorbs light that passes through the photo diodePD and enters the memory MEM, and thus it has been necessary to separatethe elements by a dopant made of silicon Si to provide a predeterminedspace.

For that reason, in the case where a pixel pitch is set to be constant,spaces for providing the photo diode PD and the memory MEM are limitedand are difficult to increase in a predetermined size or more. So, theincrease in saturation signal amount or in sensitivity of each of thephoto diode PD and the memory MEM is limited.

Additionally, the light that has passed through the photo diode PD ishard to completely block or absorb by the silicon Si that forms asubstrate. Thus, the light that has passed through the photo diode PDenters the memory MEM, and as a result, the photoelectric conversionoccurs in the memory MEM and this leads to the generation of aliasing insome cases.

In this regard, in the present disclosure, a thin separation film thatblocks or absorbs the light passing through the photo diode PD isprovided between the photo diode PD and the memory MEM, and thus thegeneration of aliasing is suppressed. Additionally, the spaces for thephoto diode PD and the memory MEM are increased in size, and thus thesaturation signal amount is increased and the sensitivity of the photodiode PD is improved. Hereinafter, description will be given on asolid-state imaging device to which an embodiment of the presentdisclosure is applied.

(Circuit Configuration Example of Solid-State Imaging Device to whichEmbodiment of Present Disclosure is Applied)

Before description is given on a solid-state imaging device to which anembodiment of the present disclosure is applied, first, an electricalcircuit configuration example of the solid-state imaging device to whichan embodiment of the present disclosure is applied will be describedwith reference to FIG. 2. It should be noted that FIG. 2 shows a circuitconfiguration example of one pixel in the solid-state imaging device.Actually, the same circuit is formed for each of a plurality of pixelsforming a pixel array.

The circuit configuration of one pixel in the solid-state imaging deviceincludes a photo diode PD, transistors Tr1 to Tr5, and drain terminalsDR1 and DR2.

The photo diode PD performs photoelectric conversion on incident light,generates charge corresponding to the amount of received light, andaccumulates the generated charge.

The transistor Tr1 operates based on a transfer signal supplied at apredetermined timing from a controller (not shown) via a transfer signalline T1 and transfers the charge accumulated in the photo diode PD tothe memory MEM (FIG. 3).

The transistor Tr2 operates based on a transfer signal supplied at apredetermined timing from a controller (not shown) via a transfer signalline T2 and transfers the charge accumulated in the memory MEM (FIG. 3)to the floating diffusion FD.

The transistor Tr3 operates based on a reset signal supplied at apredetermined timing from a controller (not shown) via a reset signalline RESET and discharges the charge accumulated in the floatingdiffusion FD from the drain terminal DR1.

The transistor Tr4 is what is called amplification transistor, andamplifies a voltage between a source and a drain with a voltagecorresponding to the charge accumulated in the floating diffusion FDbeing as a gate signal, to supply a pixel signal (light receivingsignal) to the transistor Tr5.

The transistor Tr5 operates based on a selection signal supplied at apredetermined timing from a controller (not shown) via a selectionsignal line SEL and outputs the pixel signal supplied from thetransistor Tr4 functioning as an amplification transistor to a verticalsignal line L.

(First Structure Example of Solid-State Imaging Device to whichEmbodiment of Present Disclosure is Applied)

Next, a first structure example of a solid-state imaging device to whichan embodiment of the present disclosure is applied will be describedwith reference to FIG. 3. It should be noted that FIG. 3 shows astructure example of a cross section of a side surface of a substratethat is made of silicon Si and forms a solid-state imaging devicecorresponding to one pixel, and shows that light comes from the bottomof FIG. 3 in an upward direction.

An incident surface formed by the lower portion of the substrate made ofsilicon Si is provided with a microlens ML, and the microlens ML inputsthe incident light into a color filter CF. The color filter CF isprovided with a filter of a predetermined color, for example, R, G, or B(Red, Green, or Blue), and adds a color to the incident light input viathe microlens ML and inputs the incident light into a photo diode PD.Further, though not shown in FIG. 3, the incident surface is providedwith a light blocking portion between pixels, in addition to the colorfilter CF and the microlens ML. Thus, light blocking between pixels isperformed.

The photo diode PD formed of an implant ni and an implant pi is providedon the color filter CF of FIG. 3. The implant ni is formed of an n-typeelement and formed on the substrate, and the implant pi is formed of ap-type element and formed on the implant ni.

On the other hand, the memory MEM and the floating diffusion FD areformed on the upper portion of the substrate of FIG. 3. Further, thetransistor Tr1 including a vertical transistor that transfers the chargeaccumulated in the photo diode PD to the memory MEM is provided on theupper surface portion of the substrate. Further, the transistor Tr2 fortransferring the charge accumulated in the memory MEM to the floatingdiffusion FD is provided on the upper surface of the substrate.

The photo diode PD and the memory MEM each have a HAD (Hole AccumulationDiode) structure including a hole accumulation layer on its frontsurface, the structure reducing noise by suppressing the generation of adark current occurring from the front surface.

Further, a separation film F is provided between the photo diode PD andthe memory MEM. The separation film F blocks or absorbs light that maypass through the photo diode PD and enter the memory MEM. An insulatingfilm IF is formed between the separation film F and silicon Si formingthe substrate, around the separation film F, and is in an electricallyisolated state.

It should be noted that the transistor Tr1 formed of a verticaltransistor is formed by penetrating the separation film F, engraving avertical poly-Si (polysilicon), and making the surface as a channel, andis configured to connect ends of the photo diode PD and the memory MEMso as to fall within the pitch of the photo diode PD.

Further, the separation film F is formed as a light blocking film, whichblocks light that may pass through the photo diode PD and enter thememory MEM, of a metal film made of tungsten or the like, for example.In the case where the separation film F is formed of a metal film, theseparation film F has a film thickness set to about several hundreds ofnm and is connected to an electrode (not shown) in an area outside thepixel array. This allows electrons around the separation film F fromfloating.

In such a manner, since the separation film F formed of the lightblocking film blocks the light that passes through the photo diode PD,aliasing generated in the memory MEM can be reduced. Further, sincelight blocking can be performed if a space for providing the separationfilm F is provided between the photo diode PD and the memory MEM, it ispossible to omit a space used for reducing the light that passes throughthe substrate when silicon Si is used to form the substrate. As aresult, the spaces for the photo diode PD and the memory MEM can beincreased in size, and thus the saturation signal amounts can beincreased. Further, for the photo diode PD, the saturation signal amountcan be increased and its sensitivity can be improved.

Furthermore, the separation film F can also be formed as a lightabsorbing film, which absorbs light that may pass through the photodiode PD and enter the memory MEM, of a compound semiconductor having achalcopyrite structure, for example. Examples of the compoundsemiconductor having a chalcopyrite structure include CuInSe₂. In thecase where the separation film F is formed of the compound semiconductorhaving the chalcopyrite structure, the film thickness thereof is set toabout several hundreds of nm to several μm. Further, other examples ofthe compound semiconductor having the chalcopyrite structure mayinclude, in addition to CuInSe₂, a compound semiconductor made ofcopper-aluminum-gallium-indium-sulfur-selenium-based mixed crystal or acompound semiconductor made ofcopper-aluminum-gallium-indium-zinc-sulfur-selenium-based mixed crystal.Other compound semiconductors may also be used as long as they arecompound semiconductors each having the chalcopyrite structure capableof absorbing light.

In such a manner, since the separation film F formed of the lightabsorbing film absorbs the light that passes through the photo diode PD,aliasing generated in the memory MEM can be reduced. Further, sincelight absorption can be performed if a space for providing theseparation film F is provided between the photo diode PD and the memoryMEM, it is possible to omit a space used for reducing the light thatpasses through the substrate when silicon Si is used to form thesubstrate. As a result, the spaces for the photo diode PD and the memoryMEM can be increased in size, and thus the saturation signal amounts canbe increased. Further, for the photo diode PD, the saturation signalamount can be increased and its sensitivity can be improved.

2. Second Embodiment Second Structure Example of Solid-State ImagingDevice to which Embodiment of Present Disclosure is Applied

In the above description, the example in which the transistor Tr1 formedof the vertical transistor is configured to connect the ends of thephoto diode PD and the memory MEM so as to fall within the pitch of thephoto diode PD has been described. In such a case, the maximum distancein which the charge within the photo diode PD moves to the verticalpoly-Si is equal to a width in a horizontal direction of the photo diodePD. However, when the end of the poly-Si transistor Tr1 formed of thevertical transistor is configured to come into contact with the vicinityof the center in the horizontal direction of the photo diode PD, themaximum movement distance of the charge within the photo diode PD can bereduced to half of the width in the horizontal direction of the photodiode.

FIG. 4 shows a second structure example of a solid-state imaging devicein which the end of the poly-Si transistor Tr1 formed of the verticaltransistor is configured to come into contact with the vicinity of thecenter in the horizontal direction of the photo diode PD. It should benoted that configurations having the same functions as those of theconfiguration of the solid-state imaging device of FIG. 3 are denoted bythe same reference symbols and provided with the same names, anddescription thereof will be omitted as appropriate.

Specifically, the solid-state imaging device of FIG. 4 has a differentconfiguration from the solid-state imaging device of FIG. 3, in that theend of the poly-Si transistor Tr1 formed of the vertical transistor isconfigured to come into contact with the vicinity of the center in thehorizontal direction of the photo diode PD. It should be noted that inFIG. 4, since the position of the photo diode PD with respect to thetransistor Tr1 is shifted to the right-hand side of FIG. 4 in thehorizontal direction, the microlens ML and the color filter CF of FIG. 4are also shifted in the horizontal direction similar to the photo diodePD, with respect to the microlens ML and the color filter CF of FIG. 3.

Specifically, with such a configuration, it is possible to reduce themaximum distance, in which the charge within the photo diode PD reachesthe end of the poly-Si transistor Tr1 formed of the vertical transistor,to half of the width in the horizontal direction of the photo diode PD.Consequently, the solid-state imaging device of FIG. 4 can not onlyproduce the same effects as those in the solid-state imaging device ofFIG. 3 but also shorten a charge transfer time.

3. Third Embodiment Third Structure Example of Solid-State ImagingDevice to which Embodiment of Present Disclosure is Applied

In the above description, the example in which the transistor Tr1 isformed of the vertical transistor has been described. However, it may bepossible to use the transistor Tr1 as a normal horizontal transistor andto connect the transistor Tr1 to the photo diode PD with an implant pluginstead of the p-type dopant.

FIG. 5 shows a third structure example of a solid-state imaging devicein which the transistor Tr1 is used as a normal horizontal transistorand the photo diode PD and the memory MEM are connected to each otherwith an implant plug instead of the poly-Si. It should be noted that inthe solid-state imaging device of FIG. 5, configurations having the samefunctions as those of the configuration of the solid-state imagingdevice of FIG. 3 are denoted by the same reference symbols and providedwith the same names, and description thereof will be omitted asappropriate.

Specifically, the structure example of the solid-state imaging device ofFIG. 5 is different from the structure example of the solid-stateimaging device of FIG. 3 in that a transistor Tr11 formed of a normalhorizontal transistor and an implant plug IP are provided instead of thetransistor Tr1 formed of the vertical transistor.

The function of the transistor Tr11 is basically the same as that of thetransistor Tr1, but the charge is transferred via the implant plug IPinstead of the poly-Si.

With such a configuration, it is possible to block or absorb lightpassing through the photo diode PD by the separation film F and toincrease in size the spaces of the photo diode PD and the memory MEM, asin the solid-state imaging device of FIG. 3.

As a result, the generation of aliasing in the memory MEM can besuppressed and the saturation signal amounts of the photo diode PD andthe memory MEM can be increased. Further, for the photo diode PD, thesaturation signal amount can be increased and its sensitivity can alsobe improved.

4. Fourth Embodiment Fourth Structure Example of Solid-State ImagingDevice to which Embodiment of Present Disclosure is Applied

In the above description, the example in which a two-layered structureis formed has been described, the two-layered structure including alayer as the upper surface of the substrate in the figures, on which thememory MEM and the floating diffusion FD are formed, and a layer of thephoto diode PD as the lower surface, with the separation film F beingsandwiched between the upper surface and the lower surface. However, itmay be possible to laminate the floating diffusion FD on the memory MEMto form a three-layered structure of the floating diffusion FD, thememory MEM, and the photo diode PD.

FIG. 6 shows a fourth structure example of a solid-state imaging devicehaving a three-layered structure of the floating diffusion FD, thememory MEM, and the photo diode PD by lamination of the floatingdiffusion FD on the memory MEM. It should be noted that in thesolid-state imaging device of FIG. 6, configurations having the samefunctions as those of the configuration of the solid-state imagingdevice of FIG. 3 are denoted by the same reference symbols and providedwith the same names, and description thereof will be omitted asappropriate.

Specifically, the structure example of the solid-state imaging device ofFIG. 6 is different from the structure example of the solid-stateimaging device of FIG. 3 in that the floating diffusion FD is laminatedon the memory MEM, to form a three-layered structure of the floatingdiffusion FD, the memory MEM, and the photo diode PD.

With such a configuration, it is possible to increase a space ensuredfor the memory MEM in size while keeping pitches between pixels.Consequently, the solid-state imaging device of FIG. 6 can produce thesame effects as those in the solid-state imaging device of FIG. 3 andfurther increase the saturation signal amount of the memory MEM.

5. Fifth Embodiment First Method of Manufacturing Solid-State ImagingDevice to which Embodiment of Present Disclosure is Applied

Next, with reference to FIGS. 7 and 8, a first method of manufacturing asolid-state imaging device to which an embodiment of the presentdisclosure is applied will be described. It should be noted that here amethod of manufacturing the solid-state imaging device of FIG. 3 isdescribed with reference to a flowchart of FIG. 7, but otherconfigurations are also manufactured by basically the same method.

Specifically, in Step S11, an SCF (Si Cover Film) (not shown) formed ofa hole accumulation layer including a negative fixed charge is formed oneach of a surface of a photo diode PD substrate that is shown on thelower side in a state St1 of FIG. 8, and a surface of a wiring substratethat is shown on the upper side in the state St1 of FIG. 8, the surfacesbeing opposed to each other. Subsequently, insulating films IF indicatedby bold black lines of FIG. 8 are formed on the SCFs, and separationfilms F1 and F2 are formed on the insulating films IF. It should benoted that the SCF is not an indispensable configuration, and thus aconfiguration having no SCF may be adopted.

At that time, a through-hole is formed as a pattern for forming achannel, made of poly-Si, of the transistor Tr1 serving as a verticaltransistor. It should be noted that the SCF is formed, and thus a HAD(Hole Accumulation Diode) structure is provided to the bonded surfaces,and the generation of a dark current is suppressed. However, the SCF isnot an indispensable configuration and may be omitted. Further, in thecase where the separation films F1 and F2 (separation film F) are eachmade of a compound, the insulating film IF is an indispensableconfiguration, but in the case where the separation films F1 and F2 areeach made of a metal film, the insulating film IF is not anindispensable configuration and may be omitted.

In Step S12, an n-type implant and a p-type implant are formed in thephoto diode PD substrate shown on the lower side in the state St1 ofFIG. 8, and thus a photo diode PD having a HAD structure is formed.

In Step S13, as shown in a state St2 of FIG. 8, the photo diode PDsubstrate and the wiring substrate are bonded to each other. In such amanner, the separation films F1 and F2 are bonded to each other, andthus a separation film F in a state being surrounded by the insulatingfilm is integrally formed in the upper layer of the photo diode PD,which is the lower payer of the substrate made of silicon Si.

In Step S14, as shown on the upper side in the state St2 of FIG. 8, anarea Z1 on the upper surface of the wiring substrate is polished by CMP(Chemical Mechanical Polishing) to thin the surface.

In Step S15, as shown in a state St3 of FIG. 8, wiring including amemory MEM, a floating diffusion FD, and transistors Tr1 and Tr2 isformed on the upper portion of the substrate made of silicon Si in FIG.8. At that time, a support substrate is further bonded to the upperportion of the wiring. The support substrate may be a logic circuitsubstrate for image processing, for example.

In Step S16, as shown in a state St4 of FIG. 8, an area Z2 on thesurface of the photo diode PD is polished such that the photo diode PDprovided on the lower portion of the substrate made of silicon Si inFIG. 8 has a thickness with which light of a wavelength to be absorbedis easy to absorb. The target film thickness of the photo diode PD atthat time is about several μm, for example.

In Step S17, as shown in a state St5 of FIG. 8, a microlens ML and acolor filter CF are formed.

By the manufacturing method as described above, the separation film Fthat blocks or absorbs light passing through the photo diode PD isformed between the layer in which the photo diode PD is formed and thelayer in which the memory MEM is formed. Thus, the generation ofaliasing in the memory MEM can be suppressed. Further, the separationfilm F is an extremely-thin film as compared with the substrate materialmade of silicon Si in related art and can block or absorb light thatpasses through the photo diode PD, and thus it is possible to increasein size spaces for forming the photo diode PD and the memory MEM in thesubstrate without changing a pitch per pixel and to increase thesaturation signal amounts of the photo diode PD and the memory MEM.Further, for the photo diode PD, the saturation signal amount can beincreased as described above and its sensitivity can also be improved.

6. Sixth Embodiment Second Method of Manufacturing Solid-State ImagingDevice to which Embodiment of Present Disclosure is Applied

In the above description, the example in which the photo diode PD isprovided on the photo diode PD substrate, the SCFs, the insulating filmsIF, and the separation films F1 and F2 are provided on the opposedsurfaces of the photo diode PD substrate and the wiring substrate, thephoto diode PD substrate and the wiring substrate are bonded to eachother such that the separation films F1 and F2 face each other to formthe separation film F, and wiring and the like are provided has beendescribed.

Incidentally, the photo diode PD is subjected to defect correction byannealing after implantation. In the current technology, however, laserannealing enables a local heat application, but has a difficulty incontrolling the depth of the photo diode PD. For that reason, it isnecessary to form and anneal the photo diode PD before the photo diodePD substrate and the wiring substrate are bonded to each other.

However, when the technology of laser annealing is improved in thefuture and the photo diode PD is subjected to defect correction and if athermally-formed area can be controlled to the thickness thereof, it isalso possible to provide the photo diode PD after bonding the substratesto each other and providing the wiring and the like.

FIG. 9 is a flowchart for describing a second method of manufacturing asolid-state imaging device, in which a photo diode PD is provided aftera photo diode PD substrate and a wiring substrate are bonded to eachother and wiring and the like are provided. It should be noted that theprocess steps of Step S21 to S25 and S27 in the flowchart of FIG. 9 arethe same as those of Steps S11 and S13 to S17 in the flowchart of FIG.7, and thus description thereof will be omitted.

The flowchart of FIG. 9 is different from the flowchart of FIG. 7 inthat the process step of forming the photo diode PD is performed in StepS26, which is performed later than Step S22 as the process step ofbonding the photo diode PD substrate and the wiring substrate to eachother.

Specifically, in the second manufacturing method, the process steps ofSteps S21 to S25 are first performed as shown in the states St11 to St14of FIG. 10, as follows: a separation film F is formed; a photo diode PDsubstrate and a wiring substrate are bonded to each other; an area Z11is polished to thin the wiring substrate; wiring and the like areformed; and an area Z12 is polished and thus the photo diode PDsubstrate is thinned. After those process steps area performed, as shownin the state St15 of FIG. 10, a photo diode PD is formed in a statewhere the film thickness is adjusted, by laser annealing in the processstep of Step S26.

By the manufacturing method as described above, the separation film Fthat blocks or absorbs light passing through the photo diode PD isformed between the layer in which the photo diode PD is formed and thelayer in which the memory MEM is formed. Thus, the generation ofaliasing in the memory MEM can be suppressed. Further, the separationfilm F is an extremely-thin film as compared with the substrate materialmade of silicon Si in related art and can block or absorb light thatpasses through the photo diode PD, and thus it is possible to increasein size spaces for forming the photo diode PD and the memory MEM in thesubstrate without changing a pitch per pixel and to increase thesaturation signal amounts of the photo diode PD and the memory MEM.Further, for the photo diode PD, the saturation signal amount can beincreased as described above and its sensitivity can also be improved.

It should be noted that the embodiments of the present disclosure arenot limited to the embodiments described above and can be variouslymodified without departing from the gist of the present disclosure.

Further, the present disclosure can have the following configurations.

(1) A solid-state imaging device including a lamination-type backsideillumination CMOS (Complementary Metal Oxide Semiconductor) image sensorhaving a global shutter function, the solid-state imaging deviceincluding

-   -   a separation film including one of a light blocking film and a        light absorbing film between a memory and a photo diode.        (2) The solid-state imaging device according to (1), further        including a vertical transistor configured to transfer charge        from the photo diode to the memory.        (3) The solid-state imaging device according to (2), further        including a floating diffusion, in which    -   the vertical transistor is disposed at an end of the photo diode        such that a pitch of the photo diode coincides with a pitch of        the vertical transistor, the memory, and the floating diffusion.        (4) The solid-state imaging device according to (2), further        including a floating diffusion, in which    -   the vertical transistor is disposed at the center of the photo        diode such that a pitch of the photo diode coincides with a        pitch of the vertical transistor, the memory, and the floating        diffusion.        (5) The solid-state imaging device according to any one of (1)        to (4), further including a floating diffusion, in which    -   the photo diode, the memory, and the floating diffusion are        provided on respective layers and laminated on one another, to        form a three-layer structure.        (6) The solid-state imaging device according to any one of (1)        to (5), in which    -   the separation film including the light blocking film is formed        of metal.        (7) The solid-state imaging device according to (6), in which    -   a negative potential is applied to the separation film including        the light blocking film and being formed of metal.        (8) The solid-state imaging device according to (6), in which    -   the separation film including the light blocking film and being        formed of metal is connected to an outside of a pixel array.        (9) The solid-state imaging device according to any one of (1)        to (8), in which    -   the separation film including the light absorbing film includes        a film formed of a compound semiconductor having a chalcopyrite        structure.        (10) An electronic apparatus including a solid-state imaging        device including a lamination-type backside illumination CMOS        (Complementary Metal Oxide Semiconductor) image sensor having a        global shutter function, the electronic apparatus including    -   a separation film including one of a light blocking film and a        light absorbing film between a memory and a photo diode.        (11) A method of manufacturing a solid-state imaging device        including a lamination-type backside illumination CMOS        (Complementary Metal Oxide Semiconductor) image sensor having a        global shutter function, the solid-state imaging device        including a separation film including one of a light blocking        film and a light absorbing film between a memory and a photo        diode, the method including:    -   a first step of forming an insulating film on one surface of a        first substrate on which the memory is formed and an insulating        film on one surface of a second substrate on which the photo        diode is formed, and forming the separation film on the        insulating film of the first substrate and the separation film        on the insulating film of the second substrate;    -   a second step of bonding the first substrate and the second        substrate to each other, with the surface of the first substrate        on which the separation film is formed and the surface of the        second substrate on which the separation film is formed facing        each other, to form an integrated substrate; and    -   a third step of thinning the integrated substrate.        (12) The method of manufacturing a solid-state imaging device        according to (11), in which    -   the first step includes forming an SCF (Si cover film) on each        of the one surface of the first substrate and the one surface of        the second substrate before the insulating films are formed.        (13) The method of manufacturing a solid-state imaging device        according to (12), further including    -   a fourth step of forming the photo diode on a surface that is        different from the surface of the second substrate on which the        insulating film is formed, after the insulating films and the        separation films are formed in the first step and before the        second step is performed.        (14) The method of manufacturing a solid-state imaging device        according to (12), further including    -   a fourth step of forming the photo diode on a surface that is        different from the surface of the second substrate on which the        insulating film is formed, after the third step is performed.        (15) A solid-state imaging device manufactured by a method of        manufacturing a solid-state imaging device including a        lamination-type backside illumination CMOS (Complementary Metal        Oxide Semiconductor) image sensor having a global shutter        function, the solid-state imaging device including a separation        film including one of a light blocking film and a light        absorbing film between a memory and a photo diode, the method        including:    -   a first step of forming an insulating film on one surface of a        first substrate on which the memory is formed and an insulating        film on one surface of a second substrate on which the photo        diode is formed, and forming the separation film on the        insulating film of the first substrate and the separation film        on the insulating film of the second substrate;    -   a second step of bonding the first substrate and the second        substrate to each other, with the surface of the first substrate        on which the separation film is formed and the surface of the        second substrate on which the separation film is formed facing        each other, to form an integrated substrate; and    -   a third step of thinning the integrated substrate.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An imaging device comprising a plurality ofpixels, at least one of the plurality of pixels including: a photodiode; a memory; a transistor configured to transfer charge from thephoto diode to the memory; and a film including a metal and disposedbetween the memory and the photo diode.
 2. The imaging device accordingto claim 1, wherein the transistor is a vertical transistor.
 3. Theimaging device according to claim 2, wherein the vertical transistor isdisposed at an end of the photo diode.
 4. The imaging device accordingto claim 3, further comprising a floating diffusion, wherein a pitch ofthe photo diode coincides with a pitch of the vertical transistor, thememory, and the floating diffusion.
 5. The imaging device according toclaim 2, wherein the vertical transistor is disposed at the center ofthe photo diode.
 6. The imaging device according to claim 5, furthercomprising a floating diffusion, wherein a pitch of the photo diodecoincides with a pitch of the vertical transistor, the memory, and thefloating diffusion.
 7. The imaging device according to claim 1, furthercomprising a floating diffusion, wherein the photo diode, the memory,and the floating diffusion are provided on respective layers andlaminated on one another, to form a three-layer structure.
 8. Theimaging device according to claim 1, wherein a negative potential isapplied to the film.
 9. The imaging device according to claim 8, whereinthe film is connected to an outside of a pixel array.